The present invention relates to flavoring and aromatic agents and to provision of products to which such agents are added including foods, particularly dairy products and coffee extracts, and including pharmaceuticals, cosmetics and perfumes, to flavor the products and so that they impart aroma, and the invention further relates to identification, isolation, preparation and use of 1-nonen-3-one.
Since the 1950's, yoghurt volatiles have given rise to much interest, and more than 60 flavour compounds have been identified so far (Maars et al., Volatile compounds in food, TNO-CIVO, Food Analysis Institute, The Nederlande, 1994). Its consumption has become very popular since the 1960's due to its delicate flavour associated with its particular texture and the claimed health benefits of lactic acid bacteria for humans. Headspace and simultaneous distillation-extraction (SDE) have been commonly used for the analysis of its flavour. Because of the low intensity of yoghurt odour, the sample is often heated to increase the volatility of the flavourings (Ulbeith et al., Assoc Off. Anal. Chem. 74, 630-634, 1991). This can alter the composition of this sensitive aroma and a mild sampling technique must be applied. Using a purge-and-trap sampling at a lower temperature, Laye and Imhof, respectively identified 23 and 33 compounds (Laye at al., J. Food Sci., 58, 991-995, 1993; Imhof et al., Lebensm. Wiss. u-Technol., 27, 265-269, 1994), but no one has determined the key volatiles responsible for the typical yoghurt aroma. Recently, Imhof et al. suggested 2,3-butanedione, 2,3-pentanedione, dimethyl sulfide and benzaldehyde to be the most potent ingredients in yoghurt aroma (Lebensm. Wiss. u-Technol., Z, 78-86. 1995).
In coffee extracts, Semmelroch et al. identified, as being involved in the aroma impact, 2-methyl propanal, 2-methyl butanal, 2,3,-butanedione, 2,3-pentanedione, 3-methyl-2-butenal and guaiacol (Lebensm-Wiss. u-Technol, 28, 310-313, 1995).
In another respect, 1-nonen-3-one has already been synthesised by oxidation of the corresponding alcohol by pyridinium chlorochromate (Corey et al., Tetrahedron Letters, 31, 2647-2650, 1975; Nakahira et al., J. Org. Chem., 57, 17-28, 1992). 1-Nonen-3-one has not been yet identified in foods, according to the recognised methods agreed by the International Organisation of the Flavour Industry (Z. Lebensm. u-Forsch, 192, 530-534, 1991).